Materials containing voids with void size controlled on the nanometer scale

ABSTRACT

The present invention provides a porous composite material in which substantially all of the pores within the composite material are small having a diameter of about 5 nm or less and with a narrow PSD. The inventive composite material is also characterized by the substantial absence of the broad distribution of larger sized pores which is prevalent in prior art porous composite materials. The porous composite material includes a first solid phase having a first characteristic dimension and a second solid phase comprised of pores having a second characteristic dimension, wherein the characteristic dimensions of at least one of said phases is controlled to a value of about 5 nm or less.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 11/190,360, filed Jul.27, 2005, the entire contents of which are incorporated herein byreference.

BACKGROUND

The present invention relates to a composite material useful insemiconductor device manufacturing, and more particular to a set ofporous composite materials in which the diameter (or characteristicdimension) of the pores and the pore size distribution (PSD) iscontrolled in a nanoscale manner. The term “nanoscale” is used herein todenote pores that are less than about 5 nm in diameter. The presentinvention also provides a method of fabricating the porous compositematerials of the present application.

Generally, the speed of an integrated microprocessor circuit can belimited by the speed of electrical signal propagation through the BEOL(back-end-of-the-line) interconnects. Ultralow k (ULK) dielectricmaterials having a dielectric constant of about 3.2 or less permit aBEOL interconnect structure to transmit electrical signals faster, withlower power loss, and with less cross-talk between metal conductors suchas, for example, Cu. Porous materials typically have a dielectricconstant that is less than the non-porous version of the same material.Typically, porous materials are useful for a range of applicationsincluding, for example, as an interlevel or intralevel dielectric of aninterconnect structure.

A typical porous dielectric material is comprised of a first solid phaseand a second phase comprising voids or pores. The terms “voids” and“pores” are used interchangeably in the present application. A commonaspect of porous materials is the problem of controlling thecharacteristic dimensions of the pores and the pore size distribution(PSD). The size and PSD have strong effects on the properties of thematerial. Specific properties that may be affected by the pores size orthe PSD of a dielectric material include, for example, electrical,chemical, structural and optical. Also, the processing steps used infabricating the BEOL interconnect structure can degrade the propertiesof an ULK dielectric, and the amount of degradation is dependant on thesize of the pores in the ULK dielectric. The foregoing may be referredto as “processing damage”. The presence of large pores (larger than themaximum in the pore size distribution) leads to excessive processingdamage because plasma species, water, and processing chemicals can moveeasily through large pores and can become trapped in the pores.

Typically, the pores in an ULK dielectric have an average size (i.e.,majority of the pores) and also have a component of the PSD that iscomprised of larger pores (on the order of a few nm) with a broaddistribution of larger sizes due to pore connection as the pore densityincreases (i.e., minority population of larger pores).

The minority population of larger pores allows both liquid and gas phasechemicals to penetrate into the ULK film more rapidly. These chemicalsare found in both wet and plasma treatments that are routinely usedduring integration of the ULK dielectric material to build aninterconnect structure.

The above-mentioned problems are not specific to porous dielectricmaterials. Instead, they are generally present in non-dielectricmaterials including, for example, semiconducting, ceramic and metal.

In view of the above, there is a need for providing composite materialsin which all the pores within the composite material are small having adiameter of about 5 nm or less and with a narrow PSD. There is also needfor providing a method of fabricating composite materials in which thebroad distribution of larger sized pores is substantially eliminatedfrom the material.

BRIEF SUMMARY

The present invention provides a porous composite material in whichsubstantially all of the pores within the composite material are smallhaving a diameter of about 5 nm or less, preferably about 3 nm or less,and even more preferably about 1 nm or less, and with a narrow PSD. Theterm “narrow PSD” is used throughout the instant application to denote ameasured pore size distribution with a full width at half maximum (FWHM)of about 1 to about 3 nm. PSD is measured using a common technique knownin the art including, but not limited to: ellipsometric porosimetry(EP), positron annihilation spectroscopy (PALS), gas adsorption methods,X-ray scattering or another method.

The inventive composite material is also characterized by thesubstantial absence of the broad distribution of larger sized poreswhich is prevalent in prior art porous composite materials. Thecomposite materials of the present invention are an advancement over theprior art, in one aspect, since they do not allow wet chemicals topenetrate beyond the exposed surfaces of the material during a wetchemical cleaning process. Moreover, the composite materials of thepresent invention are an advancement over the prior art, in a secondaspect, since they do not allow plasma treatments based on O₂, H₂, NH₃,H₂O, CO, CO₂, CH₃OH, C₂H₅OH, noble gases and related mixtures of thesegases to penetrate beyond the exposed surfaces of the material duringintegration thereof.

The term “composite material” includes dielectric materials,semiconducting materials, ceramic materials, or metals.

In broad terms, the inventive porous composite material comprises afirst solid phase having a first characteristic dimension and a secondsolid phase comprised of pores having a second characteristic dimension,wherein the characteristic dimensions of at least one of said phases iscontrolled to a value of about 5 nm or less.

In a preferred embodiment of the present invention, the porous compositematerial is a dielectric material having a dielectric constant of about3.2 or less, preferably about 3.0 or less.

In addition to providing a porous composite material, the presentinvention also provides a method of fabricating the porous compositematerial. Specifically, and in broad terms, the method of the presentinvention comprises providing at least a first precursor and a secondprecursor into a reactor chamber, wherein at least one of said first orsecond precursors is a porogen; optionally adding a flow of a gascomprising one of CO, CO₂, O₂, N₂O, N₂, Ar, He, Ne, Xe or Kr; depositinga film comprising a first phase and a second phase; and removing saidporogen from said film to provide a porous composite material comprisinga first solid phase having a first characteristic dimension and a secondsolid phase comprised of pores having at second characteristicdimension, wherein the characteristic dimensions of at least one of saidphases is controlled to a value of about 5 nm or less.

In a preferred embodiment of said method, said porogen comprises acompound having one C═C bond.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic pore size distribution of the material describedin the first embodiment of the present application.

FIG. 2 is a pictorial representation (through a cross sectional view)illustrating an interconnect structure that includes the material of thefirst embodiment of the present invention.

FIG. 3 is pictorial representation (through a cross sectional view)showing a light emitting structure that includes the material of thesecond embodiment of the present invention.

FIGS. 4A and 4B are pictorial representations (through cross sectionalviews) showing example structures using the catalyst material of thethird embodiment of the present invention.

DETAILED DESCRIPTION

The present invention, which provides porous composite materialscontaining pores with pore size control on the nanometer scale as wellas a method of fabricating the porous material, will now be described ingreater detail by referring to the following discussion. In someembodiments of the present invention, drawings are provided toillustrate structures that include the porous composite material of thepresent invention. In those drawings, the structures are not shown toscale.

The discussion that follows is broken up into different sections thatinclude various embodiments of the present invention. The first section(i.e., Embodiment 1) describes porous dielectric materials of thepresent invention and a method of fabricating the porous dielectricmaterial. The second section (i.e., Embodiment 2) describes poroussemiconducting material and a method of fabricating the same. The thirdsection of the present application (i.e., Embodiment 3) describes porouscatalyst materials and a method of forming the same, and the fourthsection (i.e., Embodiment 4) describes porous ceramic materials and amethod of making the same.

Embodiment 1

In this embodiment, porous dielectric materials having a dielectricconstant of about 3.2 or less, preferably about 3.0 or less, and evenmore preferably about 2.7 or less are provided. The dielectric materialof the present invention is comprised of a first solid phase and asecond phase that is a collection of pores. The first solid phase of theporous dielectric material of the present invention includes atoms of atleast Si, C, O and H. The first solid phase may optionally include otherelements such as, for example, N, F, Ge, B, P or any combinationthereof.

The second phase of the inventive porous dielectric material is acollection of pores having a pore size distribution (PSD) in which thePSD has a maximum that is less than about 1 nanometer, a full width athalf maximum (FWHM) in the PSD of 1-3 nm, and with a fraction less than0.1 of pores having a pore size of greater than about 1 nanometer. It isnoted that the porous dielectric material of the present invention thushas a tight PSD that is controlled within the nanoscale range.

In a preferred embodiment, the fraction of pores having a pore size ofgreater than 1 nanometer is less than 0.05. The pore size distributionof the dielectric material of the first embodiment is schematicallyshown in FIG. 1. In this drawing, the curve labeled 1 is the PSD of themajority fraction of the pores of the inventive porous dielectricmaterial, and the shaded area under Curve 1 is labeled 2, and is thefraction of the pores having a diameter of less than 1 nm. The componentof pores larger than 1 nm is labeled 4 for a typical material of theprior art, and the component of pores larger than 1 nm for the materialof the first embodiment is labeled 3. The component of pores larger than1 nm for the most preferred material of the first embodiment is thedashed line labeled 5.

The porous dielectric material of the first embodiment is made by afirst method, which is now discussed in detail. The first method isrelated to methods described in U.S. Pat. Nos. 6,147,009, 6,312,793,6,441,491, 6,437,443, 6,541,398, 6,479,110 B2, and 6,497,963, thecontents of which are incorporated herein by reference. In thedeposition process, the inventive porous dielectric material is formedby providing a mixture of at least two precursors, one of which includesa porogen, into a reactor, preferably the reactor is a PECVD reactor,and then depositing a film derived from the mixture of precursors onto asuitable substrate utilizing conditions that are effective in formingthe porous dielectric material of the present invention. Within thepresent invention, correct choice of a porogen enables the control ofthe pore size and PSD in the material of the first embodiment.Optionally, a flow of a gas comprising one of CO, CO₂, O₂, N₂O, N₂, Ar,He, Ne, Xe or Kr is added to the reactor.

The mixture of at least two precursors contains at least a firstalkoxysilane or alkoxycarbosilane precursor (liquid, gas or vapor)comprising atoms of Si, C, O, and H, and an inert carrier such as He, Aror mixtures thereof, and a porogen precursor. Within the presentinvention, the first precursor comprises any alkoxysilane molecule,including, for example, diethoxymethylsilane (DEMS),dimethylethoxysilane, dimethyldimethoxysilane,tetramethylcyclotetrasiloxane (TMCTS), or octamethylcyclotetrasiloxane(OMCTS). Other alkoxysilanes are also contemplated in the presentinvention and, as such, the present invention is not limited to thespecific list of alkoxysilanes provided herein.

In addition to the first precursor, a second precursor (gas, liquid orvapor) is used. The second precursor in the first embodiment of thepresent invention is a porogen such as a hydrocarbon with one doublebond (i.e., an alkene molecule). The size of the alkene precursor isadjusted in order to adjust the typical dimension of the pores (the sizeof the maximum in the PSD). Referring to FIG. 1, curve 3 shows aschematic result obtained using 1-butene as the second precursor.

The second precursor employed in this embodiment of the presentinvention includes, but is not limited to: ethylene, propylene, butene,pentene, hexene, heptene, octene, and larger alkenes with greater than8, preferably greater than 10, carbon atoms. The second precursor mayalso comprise a cyclic alkene containing at least one C═C double bond.

The present invention yet further provides for optionally adding anoxidizing agent such as O₂, N₂O, CO₂ or a combination thereof to the gasmixture, thereby stabilizing the reactants in the reactor and improvingthe properties and uniformity of the porous dielectric material beingdeposited. Optionally, a flow of a gas comprising one of CO, N₂, Ar, He,Ne, Xe or Kr may be added to improve the film.

The method of the present invention may further comprise the step ofproviding a parallel plate reactor, which has an area of a substratechuck from about 85 cm² to about 750 cm², and a gap between thesubstrate and a top electrode from about 1 cm to about 12 cm. A highfrequency RF power is applied to one of the electrodes at a frequencyfrom about 0.45 MHz to about 200 MHz. Optionally, an additional RF powerof lower frequency than the first RF power can be applied to one of theelectrodes.

The conditions used for the deposition step may vary depending on thedesired final dielectric constant of the porous dielectric material ofthe present invention. Broadly, the conditions used for providing astable porous dielectric material comprising elements of Si, C, O, andH, and having a tensile stress of less than 60 MPa, an elastic modulusfrom about 2 to about 15 GPa, and a hardness from about 0.2 to about 2GPa include: setting the substrate temperature within a range from about100° C. to about 425° C.; setting the high frequency RF power densitywithin a range from about 0.1 W/cm² to about 2.0 W/cm²; setting thefirst liquid precursor flow rate within a range from about 10 mg/min toabout 5000 mg/min, setting the second liquid precursor flow rate withina range from about 10 mg/min to about 5,000 mg/min; optionally settingthe inert carrier gases, such as helium (or/and argon) flow rate withina range from about 10 sccm to about 5000 sccm; setting the reactorpressure within a range from about 1000 mTorr to about 10,000 mTorr; andsetting the high frequency RF power within a range from about 50 W toabout 1000 W. Optionally, a lower frequency power may be added to theplasma within a range from about 20 W to about 400 W. When theconductive area of the substrate chuck is changed by a factor of X, theRF power applied to the substrate chuck is also changed by a factor ofX. When an oxidizing agent is employed in the present invention, it isflowed into the reactor at a flow rate within a range from about 10 sccmto about 1000 sccm.

While liquid precursors are used in the above example, it is known inthe art that the organosilicon gas phase precursors (such astrimethylsilane) can also be used for the deposition. Optionally, afterthe as deposited film is prepared, a cure or treatment step may beapplied to the film, according to the details described below.

An example of the first method of the present invention is now describedto make the material of the first embodiment.

A 300 mm or 200 mm substrate is placed in a PECVD reactor on a heatedwafer chuck at 300°-425° C. and preferably at 350°-400° C. Any PECVDdeposition reactor may be used within the present invention. Gas andliquid precursor flows are then stabilized to reach a pressure in therange from 1-10 Torr, and RF radiation is applied to the reactorshowerhead for a time from about 5 to about 500 seconds. Optionally, aflow of a gas comprising one of CO, CO₂, O², N₂O, N₂, Ar, He, Ne, Xe orKr is added to the reactor.

For the growth of the material of the first embodiment either one or twoprecursors may be used, as described in U.S. Pat. Nos. 6,147,009,6,312,793, 6,441,491, 6,437,443, 6,541,398, 6,479,110 B2, and 6,497,963,the contents of which are incorporated herein by reference. The firstprecursor may be DEMS (diethoxymethylsilane) or any of the abovementioned first precursors.

The second precursor is a nanoscale porogen used to prepare films withpore size controlled on the scale of about 1 nanometer. Within theinvention, the nanoscale porogen produces hydrocarbon radicals in thePECVD plasma with a limited distribution of sizes of radicals. This isdone by choosing porogens containing one C═C double bond (known asalkenes), so the radicals in the plasma have one primary reactive site(the excited C═C, which may be abbreviated as *C—C* with a radical oneach carbon).

Within the invention, other hydrocarbon molecules with one reactive site(including, for example, HO—R, alcohols, etc.) may be used. Examples ofpreferred nanoscale porogens are ethylene, propylene, butene, pentene,hexene, heptene, octene, and larger alkenes with greater than 8 carbonatoms, and linear or cyclic alkenes containing one C═C double bond.

Also, within the invention, a single alkoxysilane precursor may be usedand said precursor then contains a built-in porogen consisting of atleast one C═C double bond in the alkoxysilane precursor, and mayoptionally comprise one of vinyldimethylethoxysilane,vinylmethyldiethoxysilane, allylazadimethoxysilacyclopentane,allylaminopropyltrimethoxysilane, allyldimethoxysilane,allyldimethylsilane, allyloxy-t-butyldimethylsilane,allyloxytrimethylsilane, allyltetramethyldisiloxane,allyltriethoxysilane, allyltrimethoxysilane,bicycloheptenylethyltrimethoxysilane, bicycloheptenyltriethoxysilane,bisallyloxymethyltrimethylsiloxybutane,bisbicycloheptenylethyltetramethyldisiloxane,bistrimethylsiloxycyclobutene, butenyltriethoxysilane,butenyltrimethylsilane, (t-butyldimethylsiloxy)butyne,cyclohexenylethyltriethoxysilane, cyclohexenyltrimethoxysilane,cyclopentadienylpropyltriethoxysilane, cyclopentenyloxytrimethylsilane,cyclopentyltrimethoxysilane, diallyltetramethyldisiloxane,diethoxysilacyclopentene, divinyldiphenyldimethyldisiloxane,divinyldiphenyltetramethyldisiloxane, divinyltetraphenyldisiloxane,divinyltetramethyldisiloxane, divinyldimethylsilane,octenyltrimethoxysilane, octenyldimethylsilane, propenyltrimethylsilane,trimethylsilylcyclopentene, trivinylcyclotrisiloxane,trivinyltrisiloxane, trivinyltrimethylcyclotrisiloxane,trivinylpentamethyltrisiloxane, trivinylmethoxysilane,vinyldimethylethoxysilane, vinylmethyldiethoxysilane,vinylmethyldimethoxysilane, vinylmethylethoxysilane,vinylmethyldiethoxysilane, vinylmethyldimethoxysilane,vinylpentamethyldisiloxane, vinyltetramethyldisiloxane,vinyltri-t-butoxysilane, vinyltriethoxysilane,vinyltriisopropenoxysilane, vinyltriisopropoxysilane, andvinyltrimethoxysilane.

After deposition, the as deposited material is typically cured ortreated using thermal, UV light, electron beam irradiation, chemicalenergy, or a combination of more than one of these, forming the finalfilm having the desired mechanical and other properties describedherein. For example, after deposition a treatment of the dielectric film(using both thermal energy and a second energy source) may be performedto stabilize the film and obtain improved properties. The second energysource may be electromagnetic radiation (UV, microwaves, etc.), chargedparticles (electron or ion beam) or may be chemical (using atoms ofhydrogen, or other reactive gas, formed in a plasma).

In a preferred treatment, the substrate containing the film depositedaccording to the above process is placed in a ultraviolet (UV) treatmenttool, with a controlled environment (vacuum or reducing environmentcontaining H₂, or an ultra pure inert gas with a low O₂ and H₂Oconcentration). A pulsed or continuous UV source may be used, asubstrate temperature of 300°-450° C. may be used, and at least one UVwavelength in the range of 170-400 nm may be used. UV wavelengths in therange of 190-300 nm are preferred within the invention.

Within the invention, the UV treatment tool may be connected to thedeposition tool (“clustered”), or may be a separate tool. Thus, as isknown in the art, the two process steps will be conducted within theinvention in two separate process chambers that may be clustered on asingle process tool, or the two chambers may be in separate processtools (“declustered”).

The porous dielectric material of the present invention can be used inany semiconductor structure that requires the presence of a dielectricmaterial. One example of such a semiconductor structure is shown in FIG.2. Specifically, FIG. 2 shows a typical interconnect structure thatincludes a substrate 10 that may be semiconducting, insulating,conductive or any combination thereof, a porous dielectric material 12of the present invention including conductive features 14 embeddedtherein. The conductive features 14 are in the form of conductive viasand lines. The conductive features 14 may be insulated from thedielectric material by a diffusion barrier 16 such as TaN or TiN. Adielectric capping layer 18 is typically located atop the dielectricmaterial 12 and the conductive features 14 to contain the metal withinthe conductive features 14. The structure shown in FIG. 2 is fabricatedusing techniques, such as single damascene and dual damascene, that arewell known to those skilled in the art.

Embodiment 2

In this embodiment, porous semiconducting materials are formed. The term“semiconducting” includes any element or compound having electricalconductivity intermediate between an insulator and a conductor. Examplesof semiconducting materials that can be used in the present inventioninclude, but are not limited to: Si, SiGe, SiGeC, SiC, Ge, GaAs, InAs,InP, AlN, GaN, InN, ternary alloys of Al, Ga, In, As, P, or N,silicon-on-insulators, SiGe-on-insulators, Ge-on-insulators, and otherlike materials.

The porous semiconductor materials of the present invention can be usedas an element of a light emitting structure. Generally, light emittingstructures require a crystalline semiconductor substrate. Alsogenerally, the wavelength of the emitted light is adjusted by the bandgaps of the semiconductor layers in the structure. These band gaps canbe adjusted/modified either by doping of the crystalline semiconductoror changing the degree of crystallinity (feature size) and porosity ofthe semiconducting phase material.

The present invention provides a porous semiconducting material that maybe deposited on a non-crystalline substrate, which has the ability tochange (or adjust) the wavelength of the emitted light by adjustment ofthe feature size of the crystalline light emitting features.

The semiconducting material of this embodiment of the invention has afirst solid phase and a second phase that is a collection of poreshaving pore size controlled on the nanometer scale. The first phase iscomprised of nanometer scale, crystalline, semiconducting featurescharacterized by an optical band gap that is approximately equal to theenergy of the emitted light.

A light emitting structure of the present invention is shown in FIG. 3.In the drawing, reference numeral 50 is any substrate that meets therequirements of the structure to be made, including thermal stabilityand coefficient of thermal expansion. For example, the substrate 50 canbe glass, quartz, or a semiconductor wafer containing previouslyfabricated logic or memory circuits. On top of the substrate, aconducting bottom contact, 52, is deposited. Typically one or more metallayers will form the bottom contact 52. In a preferred structure, thebottom contact 52 is smooth and acts as a mirror to reflect emittedlight. On top of bottom contact 52 is a layer of the poroussemiconducting material 54 of this embodiment of the present invention.The porous semiconducting material is formed using the processingtechnique described herein below. A conducting and transparent topcontact 56 is located on top of the semiconducting material 54. The topcontact 56 may be a thin metal or a transparent conductor such as indiumtin oxide (ITO). Nanoscale regions 58 of top contact 56 are locatedwithin the voids in porous semiconductor material 54, and are inelectrical contact with semiconducting material 54 and top contact 56.

In the second embodiment, the inventive porous material has a firstsolid phase that is a semiconducting material with a plurality ofcrystalline features. The features are electrically connected, and eachfeature has a characteristic dimension of about 1 to about 5 nm in size.In this embodiment, the second phase is the open space between thefeatures of said first phase.

To form the structure of FIG. 3, or a related light emitting structure,the semiconducting film of this invention is deposited at a lowtemperature (on the order of about 400° C. or less, preferably less than200° C.) together with a porogen gas using either a conventional thermalchemical vapor deposition (CVD) process or a low power plasma enhancedprocess. The porogen phases are incorporated into the film at lowtemperature, but are prevented from reacting with the semiconductingphase in the as deposited film. Then, a subsequent post depositionenergy treatment is applied using thermal, UV light, E-Beam, or otherenergy (or a combination of these energy sources). During thistreatment, the porogen phase is evolved from the as deposited filmleaving the porous semiconducting material. The porogen phase is asacrificial material used to create the nanometer scale pore structure.

More specifically, this method of the present invention includes adeposition step and a separate treatment step to modify the depositedfilm. In the deposition step, a 300 mm or 200 mm substrate is placed ina CVD reactor at a temperature of less than 400° C. and preferably lessthan 200° C. Any type of CVD deposition reactor may be used within thepresent invention including, but not limited to: PECVD, thermal CVD,remote plasma CVD, Plasma Assisted Atomic Layer Deposition (ALD), AtomicLayer Deposition, and the like with single wafer or multiwafer (batch)capability. A precursor mixture comprised of gas and/or liquid precursorflows is then stabilized to reach a pressure in the range from about0.0001 to about 20 Torr for a time from about 5 to about 500 seconds.Examples of the precursors that can be used include, but are not limitedto: hydrogenated silicon sources (silane, disilane and larger silanes),hydrogenated germanium sources (GeH₄, Ge₂H₆ and the like), and hydridomolecules of other semiconducting elements such as C, Al, Ga, In, As, Por N.

Examples of preferred porogen molecules include hydrocarbons containingone double bond, including, but not limited to: propene, butene,pentene, hexane, heptene, as well as cyclic forms of these molecules.

The semiconductor film can be co-deposited in mixture of two phases, thesemiconductor and the porogen, or the film may be deposited inalternating layers of semiconductor and porogen at a low temperature(less than 400° C.).

Optionally, RF radiation is coupled to the reactor either by capacitiveor inductive coupling. Moreover, a remote plasma unit can be used insome instances to supply reactive or excited species to the reactor. Forthe growth of the semiconducting material of the second embodiment,either two or three precursors may be used. At least one of theprecursors contains at least atoms of Si, C, Ge, Ga, Al, N, In, As, Ti,Zn, or O. One of the remaining precursors is a hydrocarbon molecule, orporogen, with preferred molecules including, for example, ethylene,propylene, butene, pentene, hexene, heptene, octene, and larger alkeneswith greater than 8 carbon atoms, and the linear or cyclic alkenes.

The semiconducting film made in the deposition step includes a firstsolid phase divided into structural features that contain the atoms ofSi, C, Ge, Ga, Al, N, In, As, Ti, Zn or O. These features are typicallynot crystalline at this point, after deposition. In a later step, thefirst phase will become a semiconducting material with a plurality ofcrystalline features. As indicated above, the crystalline featurespresent in the first phase are electrically connected and each of thefeatures has a characteristic dimension of about 1 to about 5 nanometersize. This film also contains a second phase that is comprisedessentially of C and H (an organic phase) and will be removed in thetreatment step.

In the treatment step, the substrate containing the film formed in thedeposition step is heated to a temperature higher than the depositiontemperature for a time of 1 second to 4 hours, and optionally a secondenergy source is simultaneously applied. The second energy source may beUV, visible, IR or electron beam radiation, chemical or microwaveenergy. In this step, the second organic phase is removed and also thefirst phase is converted into a semiconducting material with a pluralityof crystalline features that are electrically connected. This treatmenttemperature or the temperature of a subsequent treatment is sufficientlyhigh to crystallize the semiconductor material.

In an alternative embodiment, a spraying technique (including electricfield assisted spray) that is capable of forming nano droplets ofporogen can also be used to co-deposit the semiconducting and porogenphases at low temperature to form the as deposited film.

Third Embodiment

In this embodiment of the present invention a porous catalyst materialis provided. Generally, chemically active metal catalysts aredistributed on a high surface area porous support. Also generally, thesize of the metal particles or features on the catalysts is notcontrolled and is not easily adjusted. The present invention provides ametal catalyst material that may be deposited directly on a variety ofsubstrates, producing controlled metal particles with the feature sizeadjusted in the deposition step. The applications of this materialinclude catalysts as well as sensors.

Examples of schematic structures using the material of the thirdembodiment of this invention are shown in FIGS. 4A and 4B. In FIG. 4A, aglass capillary wall 75, separates a gas flow in, 77, and a gas flowout, 79. On the walls of the capillaries 75 is a deposited metalmaterial of this invention 81, which is made according to the thirdembodiment.

In FIG. 4B, a tube or pipe, 83, has deposited on the interior wall adeposited metal material coating 81 of this invention made according tothe third embodiment. Gas flow in, 77, and out, 79, of the tube 83contain the molecules to be processed using the novel catalyst of thisinvention.

In this third embodiment, the inventive material has a first solid phasethat is a metal material with a plurality of features, in which eachfeature has a characteristic dimension from about 0.5 to about 5 nm insize. In this embodiment, the second phase is the open space between thefeatures of the first phase. The material may be deposited as a coating,as shown in FIGS. 4A and 4B.

In preferred examples of the third embodiment, the first phase is Pt,Pd, Ru, Rh, Re, Au, Ag, Ni, Fe, Co, Ti, or other catalytic metals. Theas deposited film contains a first metal phase and a second sacrificialphase. In one embodiment of the present invention, the sacrificialsecond phase within the film is non-reactive, such as the gases Xe orAr, and the film is deposited below room temperature (low temperaturedeposition). In another embodiment, the sacrificial phase is an organicphase within the film. In yet other embodiments of the presentinvention, the organic phase within the film may be formed using aporogen with one C═C double bond, such as, for example, ethylene,propylene, butene, pentene, hexene, octene, cyclic forms of thosemolecules, and larger alkenes with greater than 8 carbon atoms. In stillanother embodiment of the present invention, the organic phase may beformed using a wide range of porogen molecules including, but notlimited to: organic molecules and the porogens described in U.S. Pat.Nos. 6,147,009, 6,312,793, 6,441,491, 6,437,443, 6,541,398, 6,479,110B2, and 6,497,963, the contents of which are incorporated herein byreference.

The as deposited film is then treated in a separate subsequent energytreatment using UV, thermal, E-beam, microwave or another energy sourceas described above in the first embodiment. In a preferred example, Ptand Pd precursors containing a ligand such as cyclooctadiene (COD),hexafluoroacetylacetonate (HFAC) or C₄H₇ are used, with specificexamples being Pt(CH₃)₂(COD) and Pd(C₄H₇)(HFAC). These precursorsdecompose to deposit metal films in the temperature range from about 50°to about 100° C., and a second organic precursor may be mixed with thePt or Pd precursor. Other embodiments would include metal precursorsincluding metal alkyls, metal trifluorophospines, metal olefins,alkynes, allyls, metallocenes, metal cyclopentadienyls, metal carbonyls,metal halides, metal β-diketonates and β-ketoiminates. Generally, thesacrificial phase is an organic phase within the film. In oneembodiment, the sacrificial organic phase is produced using a secondprecursor that is selected from the group of hydrocarbons containing oneC═C double bond. This group includes, but is not limited to: ethylene,propylene, butene, pentene, hexene, heptene, octene, cyclic forms ofthese molecules and larger alkenes with greater than 8 carbon atoms. Inanother embodiment, the organic phase may be formed using a wide rangeof porogen molecules including, but not limited to: organic moleculesand the porogens described in U.S. Pat. Nos. 6,147,009, 6,312,793,6,441,491, 6,437,443, 6,541,398, 6,479,1110 B2, and 6,497,963, thecontents of which are incorporated herein by reference.

The as deposited film contains a first metal phase and a second organicphase. This film is then modified in a treatment step, in which theorganic phase is removed, leaving the porous metal material of the thirdembodiment. Optionally, the sacrificial phase is covalently bound to themetal phase in the as deposited film, and the post deposition treatmentstep removes the sacrificial second phase.

Fourth Embodiment

In this embodiment of the present invention a porous ceramic material isprovided. Specifically, the inventive material in this embodiment has afirst solid phase that is a ceramic material with a plurality offeatures, where each feature has a characteristic dimension from about0.5 to about 5.0 nanometer in size. In this embodiment, the second phaseis the open space between the features of the first phase. The firstphase may be comprised of Al₂O₃, SiO₂, an aluminosilicate, a metal oxideor nitride or carbide, or a similar stable material.

To form the material of the fourth embodiment of the present invention,two steps are used as in the above embodiments. The as deposited filmcontains a first metal phase and a second organic phase. This film isthen changed in an oxidizing treatment step, in which the organic phaseis removed and in which the metal phase becomes oxidized, leaving theporous oxide (ceramic) material of the fourth embodiment. The oxidizingtreatment step may be exposure to an oxygen (O₂) containing ambient athigh temperature (>400° C.) or exposure to an oxidizing plasma (O₂, CO₂,H₂O) at any temperature. In preferred examples of the fourth embodiment,the first phase is comprised of Al, an AlTi alloy, or an AlSi alloy. Theas deposited film also contains a second sacrificial phase that is anorganic phase and is derived from a porogen molecule such as ethylene,propylene, butene, pentene, hexene, heptene, octene, cyclic forms ofthese molecules, and larger alkenes with greater than 8 carbon atoms.

The oxidizing treatment step uses an energy source such as UV, thermal,E-beam, microwave or another energy source, and an oxidizing atmospheresuch as O₂, N₂O, or ozone. Optionally, the temperature of the oxidizingtreatment step may be from about 400° C. to about 1000° C. to ensurecomplete oxidation and formation of a stable ceramic material. Bycombining the oxidizing atmosphere with high temperature (or anotherenergy source), the first phase is converted into a metal oxide oraluminosilicate and the first phase is comprised of features each havingcharacteristic dimensions mentioned above.

Optionally, the nanoporous metal of the third embodiment of the presentinvention may be added to the porous ceramic material of the fourthembodiment, to form a catalyst material with high internal surface areaand nano-scale metal features.

While the present invention has been particularly shown and describedwith respect to preferred embodiments thereof, it will be understood bythose skilled in the art that the foregoing and other changes in formsand details may be made without departing from the spirit and scope ofthe present invention. It is therefore intended that the presentinvention not be limited to the exact forms and details described andillustrated, but fall within the scope of the appended claims.

1. A method of forming a porous composite material comprising: providingat least a first precursor and a second precursor into a reactorchamber, wherein at least one of said first or second precursor is aporogen; optionally, adding a flow of a gas comprising one of CO, CO₂,O₂, N₂O, N₂, Ar, He, Ne, Xe or Kr; depositing a film comprising a firstphase and a second phase; and removing said porogen from said film toprovide a porous composite material comprising a first solid phasehaving a first characteristic dimension and a second solid phasecomprised of pores having a second characteristic dimension, wherein thecharacteristic dimensions of at least one of said phases is controlledto a value of about 5 nm or less.
 2. The method of claim 1 wherein oneof said first or second precursors is an alkoxysilane.
 3. The method ofclaim 1 wherein said first and second precursors comprise analkoxysilane compound that has a built in porogen.
 4. The method ofclaim 1 wherein one of the first or second precursors is asemiconducting element.
 5. The method of claim 1 wherein one of thefirst and second precursors includes a metal or a material that iscapable of being formed into a ceramic.
 6. The method of claim 1 whereinsaid porogen is comprises a compound having one C═C bond.
 7. The methodof claim 6 wherein said porogen is selected from the group consisting ofethylene, propylene, butene, pentene, hexene, heptene, octene, andalkenes with greater than 8 carbon atoms.
 8. The method of claim 1wherein said removing said porogen comprises one of thermal treatment,UV treatment, treatment by electron beam irradiation, treatment withchemical energy, or a combination thereof.